The present invention relates to a silicon interposer producing method, a silicon interposer and a semiconductor device package and a semiconductor device incorporating the silicon interposer.
In the case that a semiconductor device is produced, for example, by mounting semiconductor elements on a wiring board which is made of a glass epoxy material and on which a wiring pattern is formed, by carrying out soldering or the like, it is necessary to heat the wiring board and the semiconductor elements up to the solder melting temperature. At this time, since the thermal expansion coefficient of the wiring board made of a glass epoxy material is different from that of the semiconductor elements made of silicon, cracks may occur at the connection sections between the wiring board and the semiconductor elements and the semiconductor elements may be damaged when the wiring board and the semiconductor elements become cool after the completion of the soldering processing.
For the purpose of solving the above-mentioned problem due to the difference in thermal expansion coefficient between the wiring board and the semiconductor elements, the so-called silicon interposer is known in which a silicon board made of the same material as that of the semiconductor elements is held between the wiring board and the semiconductor elements to make electrical connections between the wiring board and the semiconductor elements while relieving the stress generated owing to the difference in thermal expansion coefficient therebetween.
The semiconductor device disclosed in Patent document 1 is taken as an example of a semiconductor device incorporating such a silicon interposer. Patent document 1 describes a method for forming through-hole electrodes in a silicon board (silicon interposer). More specifically, after through-hole electrodes are formed in a silicon board, a first metal layer is formed on one face side of the silicon board and a protective tape is attached, and the first metal layer is filled into the through-hole electrodes from the other face side of the silicon board by carrying out electrolytic plating while the first metal layer is used as a power feeding layer, and then the first metal layer other than that at the periphery of the through-hole electrodes is removed.
[Patent document 1] JP-A-2006-351968
However, even in a semiconductor device incorporating a silicon interposer, at portions where the copper filled in a through-hole electrode makes direct contact with silicon oxide serving as an insulating film for protecting the wiring layer, the thermal expansion coefficient (18.3 ppm/deg C) of the copper is significantly different from the thermal expansion coefficient (0.4 ppm/deg C) of the silicon oxide, whereby there arises a problem in which cracks occur at these connection sections.